Enhanced Pseudocapacitance in Multicomponent Transition‐Metal Oxides by Local Distortion of Oxygen Octahedra |
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Authors: | Hyeon Jeong Lee Ji Hoon Lee Prof Sung‐Yoon Chung Prof Jang Wook Choi |
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Institution: | Graduate School of EEWS, KAIST Institute NanoCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea |
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Abstract: | Anomalously high pseudocapacitance of a metal oxide was observed when Ni, Co, and Mn were mixed in a solid solution. Analysis by X‐ray absorption near‐edge spectroscopy (XANES) identified a wider redox swing of Ni as the origin of the enlarged pseudocapacitance. Ab initio DFT calculations revealed that aliovalent species resulting from the copresence of multiple transition metals can generate permanent local distortions of NiO6] octahedra. As this type of distortion breaks the degenerate eg level of Ni2+, the Jahn–Teller lattice instability necessary for the Ni2+/3+ redox flip can be effectively diminished during charge–discharge, thus resulting in the significantly increased capacitance. Our findings highlight the importance of understanding structure–property correlation related to local structural distortions in improving the performance of pseudocapacitors. |
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Keywords: | electrochemistry Jahn– Teller distortion octahedron distortion pseudocapacitors solid solutions |
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